U.S. Pat. Nos. 8,453,405 and 8,713,897 of Wiercinski et al. (owned by the common assignee hereof) disclose a waterproofing membrane which is “pre-applied” by mounting it onto a building, form, or other surface, and then casting fresh concrete (“post-cast concrete”) against its adhesive layer side. The membrane design of Wiercinski et al. involves the use of a carrier sheet, a pressure sensitive adhesive (PSA), and white cement particles having particle size equal to or greater than the thickness of the PSA, such that a release sheet is not required for preventing PSA from sticking to the carrier sheet side when the membrane is rolled and unrolled. The absence of release sheet means that waste is avoided at the construction site. Eliminating the release liner means easier, faster application.
However, the present inventors believe that “pre-applied” membranes have a disadvantage. Because such membranes are installed with carrier layers facing against the installation surface (e.g., a wood form, a concrete mold), the outwardly-disposed particle-containing layers are facing towards the carrier layer of subsequently installed membranes which are overlapped at ends (side edges are sealed with 3″ PSA selvedge) to achieve monolithic protection in combination with a previously installed (adjacent) membrane. For applicators, this particles-to-carrier overlap requires extra caution, time, and effort during detailing. Sealant adhesives or mastic coatings together with suitable detailing or waterproofing tape (or strip) are usually required to ensure formation of a watertight seam along the overlapped edges of adjacent membranes.
Accordingly, the present inventors believe that a novel and inventive pre-applied-type waterproofing membrane is needed to ensure sealing and facilitate detailing at overlaps.